function modbusReadDiscreteInput()

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Read value from discrete input using modbus protocol. The call is asynchronous: the code execution proceeds immediately and when the response arrives, callback function is called.

nil modbusReadDiscreteInput(table config)

Parameters

table config{deviceAddress, callback, address,port, timeout}
  • string deviceAddress IP address of device
  • function{response} callback this function is called when response arrives
  • string address number of the coil
  • optional number port numer of port (default 502)
  • optional number timeout maximum seconds to wait for response (default 30)


Callback Parameters

table response{result, errInfo, address, value}
  • number result error code of the response (0 is success)
  • string errInfo error description (if result>0)
  • number address number of the coil
  • boolean value value of the coil

Return value

nil

Usage

-- Read value of discrete input on IP address 10.0.0.105, on port 505 with address 102
function modbusReadCallback(data)
  if data.result == 0 then
    log(string.format("modbus addr %d, got %s", data.address, tostring(data.value)))
  else
    log(string.format("modbus addr %d failed with error %d: %s", data.address, data.result, data.errorInfo))
  end
end

modbusReadCoil{deviceAddress='10.0.0.105', port=505, timeout=6, address=102, callback=modbusReadCallback}

Requirements

Netio FirmWare 3.3.0+